ExpressVPN, one of the companies, posted on its corporate site a message from Apple saying that its program was illegal in China. The British Virgin Islands-based software company says that all major virtual-private network apps were removed from the Apple app store in China. ExpressVPN claimed Apple was "aiding China's censorship effort."

Star VPN, another company, said it also received notice of being removed.

Apple said in a statement that China began requiring this year that developers of virtual-private networks have a government license. The Califronia-based tech giant said it had removed apps "in China that do not meet the new regulations."